The invention in general relates to a mining apparatus and, more particularly, to a cutting machine useful for the continuous breaking and removal of coal or other mineral from a subterranean seam thereof.
As a rule, such cutting machines are manually operated, several operators being required to perform such functions as removing bumpers attached to roof support units from the path of the approaching machine, releasing the second and subsequent roof support units behind the cutting machine and, by relaxing a hydraulic cylinder piston arrangement, moving roof support units toward the newly exposed wall of the seam, thereafter raising the roof support units again for bracing or supporting the ceiling, moving the conveyor trough by means of further hydraulic cylinder piston arrangement toward the newly exposed wall of the seam, so that behind the cutting machine, as seen in the direction of its movement, the trough and the tread-like conveyor are moved against the newly exposed seam in a generally S-shaped pattern, and moving the bumpers back into their operative position as soon as possible.
There have been proposals to automate these operations. To accomplish this the roof support units are provided with control devices. The control devices of all the roof support units are, in turn, interconnected with each other, so that any one of the control units may be actuated by any other control unit. In accordance with proposals which have become known, the leading control unit may be actuated by an infrared transmitter or an ultrasonic transmitter or by frequency signals fed through the pull chain or hawser of the machine. Depending upon the location of the transmitter on the cutting machine, the nearest control unit or the one next to it, as seen in the direction of movement of the cutting machine, is actuated for the purpose of withdrawing the forward bumper or bumpers. The control units of the first, second or third roof support structure behind the moving cutting machine, as well as any succeeding control units are actuated by the leading control unit, in order to bring about movement of the roof support structures and of the conveyor toward the mineral seam.
Such known devices have not found wide acceptance in the mining industry, possibly because they are subject to soiling and because of their inherently high potential for error signals. Such error signals may lead to considerable damage to the cutting machine or the support units.
It is an object of the invention to provide a cutting machine control which avoids the disadvantages of prior art machines and which provides for reliable automatic control.